Rotary line-switch circuit



May 6, 1930. I

H. D. SHARPE ROTARY LINE SWITCH CIRCUiT" Original Filed Dec 6. 192

co/vrncrs 4 #5 am: BEFORE CONTACTS 1-2-3 CLtSE SUCCESSII/ELY HETZ" Dar meni 51151" e Patented May 6, 1930 UNETED. ST

orri e HARRY 1). SHARPE, on mvnnroon, ENGLAND, ssienon, BY MESNE ASSIGNMENTS, T ASSOCIATED TELEPHONE & TE EGRAPH COMPANY, or KAivsAs' CITY, ivrissonnr ROTARY LINE-SWITCH CIRCUIT Application filed December 6,1926, Serial No. 152,796, and. in Great Britain March 5, 1926. Renewed 1 May 2, 1929.

This invention relates to telephone systems and is particularly concerned with an improved arrangement for reducing the unguarded interval of a line or switch after it 5 has been taken into use and for ensuring that junction circuit.

' of the type which remains on, the contactsa line relay will be fully saturated :when energized over high resistance junction lines.

Where a relay is energized over a high resistance junction line via the back contacts of a relay energized in a local circuit as soon as an idle switch or line'is seized, it has been found necessary to delay the operationof the relay energized in a local circuit to ensure full saturation of the relay energized over the This effect has been obtained by placing a small copper slug on the core ofthe relay in the local circuit, but while this arrangement ensures a satisfactory saturation of the relay in the junction circuit, it also causes the local circuit relay to be slow to operate and slow to release, thereby increasing the unguarded interval of the line which is marked engaged by the local circuit relaydue to its slowness to operate, while its increased slowness to release may cause plete a locking cricuit for itself over an auxe i'liary winding and the local circuit relay to short-circuit the auxiliary Winding. In orderthat the invention may understood and readily carried into effect, an example of the'invention will be fully, de

b an

scribed as applied to hunting switches of a type which select an idletrunk. responsive to a calling party removing his rece ver.

The single figure of drawing shows a, circuit diagram of a preferred embod ment of my invention. t, V

The drawing shows a rotary'line sw tch last used having a junction relay or line relay provided with an auxiliary winding which is energized in a local circuit before the switching relay operates and subsequent-' ly is shortcircuited by theswitching relay.

Inthe drawing, line relay L energizes over its upper winding in-series with-the incoming I negative andpo'sitive speaking conductors, via the back contacts of armaturesfi and 7 of switching relay K; Relay L upon operating actuates its contacts 1, Qtand 3, contact 1 closing firstand followed by contacts 2 and 3. If the bank contact engagedby the test eratedcOntactZ of relay L andfalso short- I circuits the auxiliary winding of relay L,

this operation rendering the relay L slowto-release. Contact 5. prepares a holding circuit for switching relay K, while contacts 6 and 7 disconnect the energizing circuit for relay Land extend the negative and positive speaking conductors .to the negativeland positive wipers. At this time relay L is slow-torelease since its, auxiliary winding is shortcircuited and relay K ismaintained energized from earth,contact 4, contact 2, contact-5, winding of relay K, winding of driving mag; net DM to battery Driving magnet DM however does not energize at this time owing to the high resistance of relay K, nor does it 7 energize when the lower'winding of Lie c-onnected in parallel with K. When the line remains on the contacts last used, it will be readily'understood by those skilled in the artthat' the invention can be'applied to a rotary lineswitch ofthe homing type by providing a linefrelay withan auxiliary lecting movement and a switching relay is. operated for seizing an idle trunk and for thereupon releasing theline relay, means for delaying the release operation of they line relay, said means including means for momentarily additionally energizing said line relay in parallel with said switching relay when the switch comes opposite an idle'trunk.

2. In a trunk selecting switch, a line relay, means for operating the line relay when the switch is taken into use to indicate a busy] condition of theswitch and to start the trunk hunting operation, means .for releasing the line relay upon the selection of a trunlnand means for momentarily delaying the releasing operation of the relay,said last means comprising a winding on the relay and means entirely within the switch for momentarily energizing and then short 'circuiting the winding; 1 V v 3. In a trunkselecting switch,;a switching relay, a line relay, means for operating the line relay, an auxiliary Winding on the line relay, means establishing under predetermined conditions a locking circuit for said line relay throughsaid auxiliary winding and contacts of said switchingrelay, and means controlled by the switching" relay for subsequently short circuiting said auxiliary winding.

LIn a trunk selecting switch, a driving magnet, a switching relay, a line relay including an'operating winding, circuit connections to said winding extending through back conworsen the switching relay, an auxiliary winding on the line relay, means establishing under predetermined conditions a circuit 'including the winding of the switching relay in parallelconnected in series with the driving magnet for operating the switching relay and locking the line relay, and means controlled by the switching relay for subsequently short circuiting the auxiliary windinga 5. In a trunk selectingfswitch, a driving magnet, a switching relay, a line relay-1ncluding an operating winding,- circuit c011- nections to said winding extending, through back contacts on the switching relay, an auxiliary winding on the line relay, means establishing under predetermined cond tionsa c rcuit including the winding of the switching relay and the said auxiliary winding of the line relay in parallel connected iniseri eswith thedriving magnet for operating the switchingrelay and locking the line relay,con'tacts controlled by the switching relay for subse quently short circuiting said auxiliary winding, and connections whereby said last mentioned contacts also mark the selected trunk busy. 7

6. In a telephone system, a trunk selecting switch normally associated with a trunk, a line relay arranged to be operated when the switch is taken into use, means controlled by the line relay for disassociating saidswitch from a busyv trunk and associating it with the next trunk, means for releaslng the line relay responslve to the selectlon of and connection with an idle trunk, and means for delaying the releasing operation of the relay, said means including means for momentarily additionally energizing said line relay only during the intervalbetwee'n the selection of the trunk andthe connection therewith.

7. In a telephone system, a trunk selecting switch having wipers normally resting on the trunk last used, a line relay, connections established when the switch is taken into use for operating the line relay, means controlled by the line relay for moving the wipers off of busy trunks,means in the switch for momentarily establishing a locking circuit for said line relay when the wipers rest upon an idle trunk and for then disabling said locking circuit independent of said wipers to release said linerelay. r

.8. In a telephone system, a trunk selecting switch having wipers normally resting on the trunk last used, a line relay, means for energizing thev line relay when the 'switch is taken into use and for deenergizing it responsive to the wipers resting on an idle trunk, means for insuring the complete energization of-said relay prior to its deenergization when the wipers happen to rest on an idle trunk'at the time eluding means for'momentarily establishing a 7 locking circuit for saturating said relay prior to'its release andmeans entirely within the switch for disabling said locking circuit.

the switch is taken into use, said'means inr 9 In a trunk selecting switch, a line relay and a switching relay, an operating circuit and the auxlhary'wmdmgof the lme relayforthe line relay including back contacts of the switching relay, a holding circuit forthe linerelay" including other back contacts of the -switching relay, and a releasing'circuit for the line relay including front contacts of the switching relay;

10. In a trunk selecting switch, a line relay,

switching relay.

11. In'a trunkselecting switchcomprising a lin'e'relay, aswitching relay and a stepping ma'gn'et, two windings tor the line relay, means for operating the line relay over one o f'said windings, and means responsive Ltoth'e operation "of'the line relay for closing a circuit for the switching relay and the mag- 7 net series,"a'nd for connecting the other of Cal said windings to said circuit at a tween the relay and the magnet.

12. In a trunk selecting switch equipped with a test wiper, a line relay having two windings, a switching relay, means for operating said line relay over one winding, means responsive to the operation of the linerelay for completing parallel circuits for the switching relay and the other winding of the line relay, and circuit connections whereby the switching relay and the said other winding are shunted as long as the test wiper engages a busy contact.

13. In a trunk selecting switch, a line relay and a switching relay, a test wiper, a locking circuit for the line relay, and two shunt circuits for rendering said locking circuit in effective, said first shunt circuit including contacts of the line relay and the test wiper, said second shunt circuit including contacts of the switching relay but excluding said test wiper. 7

14. In a trunk selecting switch equipped with a test wiper, a line relay and a switching relay, a locking circuit for said line relay,

means including the test wiper for rendering point be- HARRY D. SHARPE. 

